Flexible packaging laminated material has been used to pack liquid food for many years. A packaging container for use with milk, juice, refined sake, shochu, mineral water and other drinks is produced by: forming web-like packaging laminated material of, for example, a fibrous substrate (for example, paper)/plastic laminate, which has crease lines, into a tube shape having a longitudinal seal, as shown in FIG. 5; filling the tube-shape formed packaging material with contents; sealing the tube packaging material transversely; forming the packaging material into a cushion-like or pillow-like preliminary container; cutting the containers individually at a fixed distance in the case of the web-shaped packaging material; and folding a container corner flap along the crease lines to form a brick-shaped container. The container includes panels 3 for side walls, as shown in FIG. 4, a longitudinal seal 5, a transverse seal 6, a panel 4a forming a top wall, and flaps 8 (the corner flaps are formed when a top and bottom are formed) sealed at the side walls. As an example, a material for the fibrous substrate can be cardboard.
A gable-top paper packaging container is provided by: cutting a paper packaging material in the predetermined shape; forming blanks that are sealed in a lengthwise direction to form containers; sealing the bottom of the blanks in a filling machine; filling the formed blanks with contents of milk, juice or other drinks from an upper opening; and sealing the upper part of the containers. With these packaging materials, an appearance design of the packaging container product can be printed on the surface.
Crease lines for each container are repeatedly and continuously added to the web-shaped packaging material. FIG. 5 shows packaging material for one container. In the packaging material 1 for one container, the web-shaped packaging material having crease lines comprises a seal region 5 for forming the longitudinal seal, transverse seal regions 6 for forming a seal in a transverse direction of tube packaging material, side panels 3 that form container side walls, panels 4a for forming a top of the container, panels 4b and 4c, which are folded to form flaps 8, and are welded to the side walls or to a bottom of the container. Crease lines 7a–7c are formed at the boundaries of these panels.
In the brick-shaped container as shown in FIG. 4, transverse seal part 6 and longitudinal seal part 5 occupy the middle of the container top. Accordingly, the blank space available for applying a spout, an opening device, a lid and/or a plug is insufficient. As a result, only a comparatively small spout can be applied with a container formed in this way.
Furthermore, the sharpened four corners of the container top are points where a container is most likely to receive damage by means of a physical mechanical external effect, such as during a distribution process.
Gable top-shaped paper packaging containers, wherein the paper containers have a wide top part with an applied large-scale spout, have been proposed. (Japanese Patent Laid-Open No. 11-91792 and Japanese Patent Laid-Open No. 11-236027). However, in these containers the folding part is folded tightly toward the inside of the package by folding of the top seal fin when the shed roof shape of one sheet roof is formed from the gable top shape. This method of forming the container results in increased stresses to the packaging material as a result of the compression and tension exerted during the forming process. The strength characteristics of the resulting paper container are therefore deteriorated remarkably.
Furthermore, because it is difficult to fold a container material along the crease lines, when the asymmetric gable top shape paper packaging container is formed, a preliminary top fold formation apparatus for the paper container is proposed (Japanese Utility Model Laid-Open No. 4-53602).
However, in existing high speed packaging filling machines producing, for example, 6,000 to 15,000 containers an hour, it is difficult to interpose the tool in a container interior and to fold along the crease lines, by using the proposed preliminary fold formation apparatus.